Drill sharpening jig build.

[toglhot]

I normally sharpen drill bits by hand, it's fine for 99 percent of sharpening chores, but the jig affords a little more precision in regards to length of the point shoulders. If one shoulder is longer than the other, putting the point slightly off centre, then the size of the hole drilled reflects that, times two. For example: If one shoulder is say 0.02 mm longer than the other, the bit will drill a hole 0.04mm larger than the bit. Very rarely do I need this type of accuracy, besides a new bit will do that anyway. The jig was largely just a project.

I didn't have a mill when I made the jig, so the V and slot were done on the lathe. There is a blind hole up through the centre into which a threaded rod goes. The threaded rod is fitted with a brass bush which locates in the blind end. The other end has a small plate which is threaded for the rod. The threaded rod has two knurled thumbscrews, one for adjusting, the other for locking off. To advance the drill, simply turn the knurled knob and a nut with a fin welded on advances the bit. An H plate slides up and down in a cradle up front and clamps the drill bit in place.

The body sits atop a flat plate, angled at 118 degrees and has a 10mm wide guide screwed in place underneath. The guide fits nicely inside the track on the grinder table I made for the jig. Simply advance the drill onto the stone and slide the jig side to side, then turn the drill bit around and repeat. Indexing is by eye.

The rakes are adjusted by table angle. The jig will accommodate 3m to 13mm + or - a few mm, although anything under 3mm is very difficult to index with 70 year old eyes. I don't bother thinning the webs as the point created by the facet grind works fine for me. Plus my eyes aren't good enough for that operation.

I made a nice wooden box for it with drill sharpening jig written in Chinese script on the top, at least I hope that's what it says. Everyone knows all the best tools come from China, right? Hence the Chinese writing. That statement should generate some angst!

Now, before you tell me the shoulders on the drill pictured look to be different lengths, look at the angle of the shot.

This jig is great for sharpening drills to drill 6mm holes with 6mm drills. Actually, the hole comes out slightly smaller as drills are all slightly smaller than the nominated size.

Some pics.

[milomilo]

Originally Posted by toglhot

I normally sharpen drill bits by hand, it's fine for 99 percent of sharpening chores, but the jig affords a little more precision in regards to length of the point shoulders. If one shoulder is longer than the other, putting the point slightly off centre, then the size of the hole drilled reflects that, times two. For example: If one shoulder is say 0.02 mm longer than the other, the bit will drill a hole 0.04mm larger than the bit. Very rarely do I need this type of accuracy, besides a new bit will do that anyway. The jig was largely just a project.

I didn't have a mill when I made the jig, so the V and slot were done on the lathe. There is a blind hole up through the centre into which a threaded rod goes. The threaded rod is fitted with a brass bush which locates in the blind end. The other end has a small plate which is threaded for the rod. The threaded rod has two knurled thumbscrews, one for adjusting, the other for locking off. To advance the drill, simply turn the knurled knob and a nut with a fin welded on advances the bit. An H plate slides up and down in a cradle up front and clamps the drill bit in place.

The body sits atop a flat plate, angled at 118 degrees and has a 10mm wide guide screwed in place underneath. The guide fits nicely inside the track on the grinder table I made for the jig. Simply advance the drill onto the stone and slide the jig side to side, then turn the drill bit around and repeat. Indexing is by eye.

The rakes are adjusted by table angle. The jig will accommodate 3m to 13mm + or - a few mm, although anything under 3mm is very difficult to index with 70 year old eyes. I don't bother thinning the webs as the point created by the facet grind works fine for me. Plus my eyes aren't good enough for that operation.

I made a nice wooden box for it with drill sharpening jig written in Chinese script on the top, at least I hope that's what it says. Everyone knows all the best tools come from China, right? Hence the Chinese writing. That statement should generate some angst!

Now, before you tell me the shoulders on the drill pictured look to be different lengths, look at the angle of the shot.

This jig is great for sharpening drills to drill 6mm holes with 6mm drills. Actually, the hole comes out slightly smaller as drills are all slightly smaller than the nominated size.

Some pics.

Have you ever sharpened a drill using a Drill Doctor?

[toglhot]

Yes, and?

[LKeithR]

Drill Doctors suck......at least compared to real sharpening machines. We've had a couple and I was never happy with either. Not solid enough to provide consistent results...

[Ironman]

Originally Posted by toglhot

I normally sharpen drill bits by hand, it's fine for 99 percent of sharpening chores,

This jig is great for sharpening drills to drill 6mm holes with 6mm drills. Actually, the hole comes out slightly smaller as drills are all slightly smaller than the nominated size.

Some pics.

I find most drills are under the nominal size. Must be a reason.
I gotta compliment you on the quality and finish of the work, very nice and the chinese box is a kick. For the rest of the world US and China are all imported stuff anyway.

[greywynd]

Nice build and I like the attention to details.

I still do all my sharpening by hand. I’ve used drill doctors, darex, and a couple others. If I’m looking to be fussy I break out the drill gauge to measure and compare sides.

For small drills, and thinning webs, I’ll often use the finer wheel mounted on a surface grinder. Sharper corners, less vibration and such, just run the table to the end, tip the guard if possible and freehand it.

There was a time I would regularly sharpen drills down to .020” diameter, not sure the eyesight would let me now.


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[milomilo]

Originally Posted by toglhot

Yes, and?

And, what is your opinion on how well they work?

[terry lingle]

Don't forget that drills are intended to make approximately round holes of almost the stated size.
If You need better than that you must ream or bore the hole to the desired tolerance.
I have standard drill indexes metric drill indexes , Letter drills, number drills from 0 to 60 , prentice drills ,left hand drills
Morris taper shank drills spot facing drills , countersinking drills and probably more that I have missed.
Most are top quality drills not because they make better holes but because they make more holes between sharpenings.

Above 3/16 I can free hand sharpen and get a hole below that they are used as pins or thrown out when they get dull.

[Hoggo]

You can waste time drilling a slightly undersized hole then ream to size, but it is totally unnecessary and unnecessarily long winded for a simple bolt hole with no play.

Drill a pilot close to the required size then drilling with the right size will result in a bolt hole with no play. Provided the drill is sharpened correctly. Given the human eye is incapable of picking up size differences under around 1mm, that's where a jig comes in.

Reamers are ok for what they are meant for, but totally over the top for a simple bolt hole.

[greywynd]

Originally Posted by Hoggo

You can waste time drilling a slightly undersized hole then ream to size, but it is totally unnecessary and unnecessarily long winded for a simple bolt hole with no play.

Drill a pilot close to the required size then drilling with the right size will result in a bolt hole with no play. Provided the drill is sharpened correctly. Given the human eye is incapable of picking up size differences under around 1mm, that's where a jig comes in.

Reamers are ok for what they are meant for, but totally over the top for a simple bolt hole.

I never saw anyone mention reaming for a simple bolt hole. And actually drilling a pilot ‘close to the required size’ then drilling is actually more of a reaming operation at that point. An actual pilot hole should only be slightly larger than the web of the next size drill that is needed.


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